Vitamin D Supreme provides clinically useful amounts of vitamin D3 and vitamin K (both K1 and K2 [as MK-4]), along with geranylgeraniol (GG), a substance produced naturally in the body, to promote optimal bone and arterial health and to maintain the immune system in proper balance. The amount of vitamins D and K in this formula may be beneficial for those who do not receive adequate sun exposure and/or dietary sources of these vitamins. Vitamins D and K work synergistically, thus, increasing vitamin D increases the need for vitamin K.